As Facebook and Twitter become as central to workplace conversation as the company cafeteria, federal regulators are ordering employers to scale back policies that limit what workers can say online. ?...

But in a series of recent rulings and advisories, labor regulators have declared many such blanket restrictions illegal. The National Labor Relations Board says workers have a right to discuss work conditions freely and without fear of retribution, whether the discussion takes place at the office or on Facebook. ?...

But placing clear limits on social media posts without crossing the legal line remains difficult, said Steven M. Swirsky. "Even when you review the N.L.R.B. rules and think you're following the mandates," he said, "there's still a good deal of uncertainty."